I'm grateful for your comments, Nancy.
As far as the opening is concerned, I was following advice in one of Harry's video tutorials. He recommends using the Jane Austen "Pride And Prejudice" method, whereby she lets you know at the start what the novel is going to be about. I'm glad it had the desired effect on you!
As for being more descriptive, I wanted to avoid dragging the opening with too much of it. My idea is to spend more time on creating mood and enhancing the setting later on but I'll see if I can do a bit more on that at the beginning. I've chosen the seaside as a setting for my writing before. That's partly because I like the seaside myself and because it can provide mood and plot opportunity.
As far as describing the "hurricane" effect of the children, I would have thought that would be giving too much detail, except that you have pointed out where I can illustrate t a certain aspect of the mother-in-law's character. I just hope I won't be overloading the opening chapter.
I'm glad to know that you think I've pulled the reader in. That's the idea.